Watersheds in muskeg terrain: 2. Evaluations based on water chemistry

This paper discusses the application of data on stream water chemistry to regional groundwater evaluation, hydrograph separation, and evaluation of the effects of basin disturbance. We have selected for analysis the Firebag, Steepbank and Muskeg River basins, and Hartley and Thickwood Creek basins in northern Alberta, Canada. They cover slightly more than 9000 km 2 within a region containing vast quantities of surface mineable, oil sand deposits. All basins are drift covered and underlain by bedrock that can range in age from Precambrian to Cretaceous. Comparison of chemical data for stream water from all basins with that for groundwater from Hartley Creek basin confirms that groundwater is a major source of streamflow in winter. Indications are that this groundwater inflow is almost entirely from glacial drift. Hydrograph separations based on chemical parameters indicate that during the spring and summer the proportion of groundwater in the streamflow is less than winter values with the largest contribution by far coming from the drainage of muskeg. Muskeg thus exerts important control on stream discharge and chemistry. If surface mining in these basins causes the removal of muskeg and replacement by mineral soil, stream discharge from affected areas will be less during summer and more during spring runoff and stormflow periods. As well, major-ion concentrations should be generally higher in the summer and fall months. However, the impact of local disturbances in a larger basin will be diminished downstream as waters from affected areas are mixed with other waters.